1. Field of the Invention
The present invention relates to a thermal siphon reactor and a hydrogen generator including the same, and more particularly, to a thermal siphon reactor with self-operating ability and a hydrogen generator including the same.
2. Description of the Related Art
Technologically important gases, such as hydrogen and oxygen, have gained much attention due to the huge applications in the fields of energy, chemical and biotechnology. Although the conventional processes of their productions and separations in large quantity are well established, their small-scaled processes in the ways of cost effectiveness and high efficiency are still remained as a challenging issue.
In general, hydrogen can be provided to a fuel cell or a device using hydrogen through various methods. For example, hydrogen can be stored in the form of gas under high pressure for use, hydrogen can be stored in the form of liquid and then vaporized for use, hydrocarbons can be reformed to generate hydrogen and the hydrogen is provided, or hydrogen can be adsorbed to a hydrogen storing alloy and then desorbed for use.
Direct hydrogen storage methods are commonly used to store pure hydrogen in the form of gas or liquid. These methods require specialized and durable containers that are capable of bearing very high pressures and/or extremely low temperature.
Another common method of hydrogen generation is to use a catalytic steam reformer, which converts hydrocarbon to hydrogen and carbon dioxide. The major drawbacks of this method are time lag for starting due to the reforming process and unwanted byproducts, such as carbon monoxide and carbon dioxide. The adsorption methods for H2 storage also have numerous problems including low hydrogen density per unit volume, deterioration of the hydrogen adsorption materials, and time lag for starting due to the slow desorption kinetics for H2 generation, and so on. Recently, hydrogen generation from aqueous sodium borohydride solution using a catalyst has stirred many interests in scientific communities since it is not only stable in normal operation condition, but also releases hydrogen gas in safe and controllable way. In spite of several advantages of using sodium borohydride for hydrogen generation, hydrogen generation systems using this technology necessitate further developments in the aspect of high efficiency, reduced space for installation, and convenience.
Conventional gas generation apparatuses often have auxiliary equipments, such as a pump and a heater, which are used for reactant delivery and a heating source, respectively. These auxiliary equipments lower efficiency of energy utilization overall.